Vitamin K deficiency linked to osteoarthritis

April 11, 2006

NEW YORK (Reuters Health) – Study findings support an
association between low blood levels of vitamin K and an
increased prevalence of hand and knee osteoarthritis — the
most common form of arthritis, occurring mainly at older ages,
in which the cartilage cushioning the joints breaks down over
time, leading to pain, stiffness and, often, limited mobility.

“We are not yet sure if vitamin K is in fact the cause of
osteoarthritis,” lead author Tuhina Neogi, from Boston
University, told Reuters Health. “But what we did see is that
the lower the levels of vitamin K in the blood, the higher the
prevalence of osteoarthritis.”

The primary form of vitamin K in the diet is
“phylloquinone,” which is found mostly in green leafy
vegetables, but also in cheese, liver, coffee, and green tea,
for example. Insufficient intakes of vitamin K are not uncommon
in the US and have already been shown to cause problems of
blood coagulation in humans, according to Neogi.

“It’s a new hypothesis that vitamin K might be linked to
osteoarthritis,” said Neogi. “In animals models, there are some
bone and cartilage proteins known to be vitamin K dependent.
When those proteins don’t work properly, the animals get a lot
of bone and cartilage abnormalities, which resemble
osteoarthritis.”

Working with over 650 participants, the researchers set out
to determine whether vitamin K deficiency is associated with
features of osteoarthritis on x-ray examinations.

Results, published in the journal Arthritis and Rheumatism,
showed that patients with the lowest phylloquinone plasma
levels were also the ones whose x-rays most often revealed the
presence of large osteophytes, or “bone spurs” — small
outgrowths of the bone common in arthritis.

“If there is a causal relationship between the two, the
levels required for adequate functioning of vitamin K-dependent
bone and cartilage proteins are not yet known,” Neogi said.